iPaaS Notify by SMTP not sending attachments

We have a notification provider set up to send notifications by SMTP. It allows us to send emails appropriately form iPaaS, but it is not allowing us to send attachments via these emails.

We are using the SMTP connector.

Within the notification provider, we are not prompted to add any attachments when using this connector. 

But when using the notification provider through the "notify by SMTP" prebuilt connector, we are prompted to add attachments. But these attachments never send.

Does anyone have an idea of what we are doing wrong?

Thanks,

NB